Upcoming Planetary Probes - Missions And Schedules

CASSINI - Saturn orbiter and Titan atmosphere probe. Cassini is scheduled for launch aboard a Titan IV/Centaur in October of 1997. After gravity assists of Venus, Earth and Jupiter, the spacecraft will arrive at Saturn in June of 2004. Upon arrival, the Cassini spacecraft performs several maneuvers to achieve an orbit around Saturn. Near the end of this initial orbit, the Huygens Probe separates from the Orbiter and descends through the atmosphere of Titan. The Orbiter relays the Probe data to Earth for about 3 hours while the Probe enters and traverses the cloudy atmosphere to the surface. After the completion of the Probe mission, the Orbiter continues touring the Saturnian system for three and a half years. Titan synchronous orbit trajectories will allow about 35 flybys of Titan and targeted flybys of Iapetus, Dione and Enceladus. The objectives of the mission are threefold: conduct detailed studies of Saturn's atmosphere, rings and magnetosphere; conduct close-up studies of Saturn's satellites, and characterize Titan's atmosphere and surface.

One of the most intriguing aspects of Titan is the possibility that its surface may be covered in part with lakes of liquid hydrocarbons that result from photochemical processes in its upper atmosphere. These hydrocarbons condense to form a global smog layer and eventually rain down onto the surface. The Cassini orbiter will use onboard radar to peer through Titan's clouds and determine if there is liquid on the surface. Experiments aboard both the orbiter and the entry probe will investigate the chemical processes that produce this unique atmosphere.

GALILEO - Jupiter orbiter and atmosphere probe, in transit. Has returned the first resolved images of asteroids, Gaspra and Ida. Efforts to unfurl the stuck High Gain Antenna (HGA) have essentially been abandoned. JPL has developed a backup plan that should allow Galileo to achieve approximately 70% of its original science objectives with the much lower speed Low Gain Antenna. Long-term Jovian weather monitoring, which is imagery intensive, will suffer the most.

TOPEX/Poseidon - Joint US/French Earth observing satellite, launched 8/10/92 on an Ariane 4 booster. The primary objective of the TOPEX/POSEIDON project is to make precise and accurate global observations of the sea level for several years, substantially increasing understanding of global ocean dynamics. The satellite also will increase understanding of how heat is transported in the ocean.

ULYSSES - European Space Agency probe to study the Sun from an orbit over its poles. Launched in late 1990, it carries particles-and-fields experiments (such as magnetometer, ion and electron collectors for various energy ranges, plasma wave radio receivers, etc.) but no camera.

MARS GLOBAL SURVEYOR - Replacement for Mars Observer including most MO instruments. To be launched on a Delta II booster and begin Mars science operations in 1/98. Followon landers and orbiters are planned for launch about every 2 years for the following decade. (See page three for a detailed look at this mission).